Comment on ``Theory of Spinodal Decomposition''

I comment on a paper by S. B. Goryachev [PRL vol 72, p.1850 (1994)] that presents a theory of non-equilibrium dynamics for scalar systems quenched into an ordered phase. Goryachev incorrectly applies only a global conservation constraint to systems with local conservation laws.Comment: 2 pages LATeX (REVTeX macros), no figures. REVISIONS --- more to the point. microscopic example added, presentation streamlined, long-range interactions mentioned, to be published in Phys. Rev. Let

Non-equilibrium Phase-Ordering with a Global Conservation Law

In all dimensions, infinite-range Kawasaki spin exchange in a quenched Ising model leads to an asymptotic length-scale $L \sim (\rho t)^{1/2} \sim t^{1/3}$ at $T=0$ because the kinetic coefficient is renormalized by the broken-bond density, $\rho \sim L^{-1}$. For $T>0$, activated kinetics recovers the standard asymptotic growth-law, $L \sim t^{1/2}$. However, at all temperatures, infinite-range energy-transport is allowed by the spin-exchange dynamics. A better implementation of global conservation, the microcanonical Creutz algorithm, is well behaved and exhibits the standard non-conserved growth law, $L \sim t^{1/2}$, at all temperatures.Comment: 2 pages and 2 figures, uses epsf.st

Seeing Beyond: Real-time Ultrasound Image Integration in Augmented Reality Based Telementoring

Ultrasound imaging, when aptly integrated with augmented reality based medical telementoring, may be beneficial as an assistive tool in a range of trauma procedures including removal of foreign objects from blast injuries and central or peripheral venous access. Expected benefits include reduced procedure completion time, higher efficiency, and higher incision accuracy. This paper describes the implementation strategy selected for the integration of real time ultrasound imaging in the trainee view of a telementoring system. The proposed strategy augments the view of the trainee surgeon by displaying the ultrasound image directly below and parallel to the ultrasound transducer. The developed system features a fiducial marker based tracking approach employing a triplanar geometric fixture. An experiment was designed to demonstrate the system function and validate its performance

Carcinoma de células transicionales asociado con litiasis de la unión ureteropiélica: reporte de un caso

ResumenA continuación se reporta un caso de carcinoma de células transicionales descubierto durante una ureteroscopia indicada por litiasis de la unión ureteropiélica. Se tomó biopsia del tumor y posteriormente se realizó ureterolitotomía con biopsia transquirúrgica, identificando tumor de células transicionales por lo que se realizó nefroureterectomía derecha con resultado histopatológico de tumor de células transicionales de bajo grado. Este caso ilustra el potencial de desarrollar tumor de células transicionales en áreas afectadas por litiasis urinaria.AbstractA report is described herein of a case of transitional cell carcinoma discovered during ureteroscopy indicated for ureteropelvic junction lithiasis. A biopsy of the tumor was taken, after which ureterolithotomy with intraoperative biopsy was performed that identified a transitional cell tumor. Right nephroureterectomy was carried out and the histopathologic study reported a low-grade transitional cell tumor. This case illustrates the potential there is for developing a transitional cell tumor in areas that have been affected by urinary tract lithiasis

Entropy Production of Brownian Macromolecules with Inertia

We investigate the nonequilibrium steady-state thermodynamics of single Brownian macromolecules with inertia under feedback control in isothermal ambient fluid. With the control being represented by a velocity-dependent external force, we find such open systems can have a negative entropy production rate and we develop a mesoscopic theory consistent with the second law. We propose an equilibrium condition and define a class of external forces, which includes a transverse Lorentz force, leading to equilibrium.Comment: 10 pages, 1 figur

Optimal management of vegetation maintenance and the associated costs of its implementation in overhead power distribution systems

Los operadores de red están constantemente trabajando en mantener un nivel de confiabilidad apropiado en el suministro de energía y preservar la integridad de la vegetación que crece bajo las redes aéreas de distribución de energía. Por tal razón, en este artículo se proponen e implementan diferentes alternativas para gestionar de manera óptima el mantenimiento de la vegetación. El problema se representa a través de modelamiento matemático, en función de varios aspectos enmarcados en el manejo de la flora, basados en la capacidad técnica de la empresa y las metas de confiabilidad estipuladas por los organismos gubernamentales. En la solución del problema, se obtiene un programa de mantenimiento de la vegetación en términos de cuándo y dónde se debe realizar este, además de la asignación de los grupos de trabajo destinados para las labores de poda a lo largo del sistema de distribución. De esta manera, se minimiza el nivel de energía no servida y se optimizan los recursos financieros necesarios para este tipo de tareas.Network operators work constantly to maintain an appropriate level of reliability in their power supply and to preserve the integrity of the vegetation growing underneath overhead power distribution systems. Accordingly, this article proposes and adopts different approaches to optimally manage vegetation maintenance in such field. Mathematical modeling is used to represent the problem in terms of several aspects involved in vegetation management, based on the technical capacity of the utility company and the reliability goals established by governmental regulatory entities. The solution is a vegetation maintenance schedule in terms of when, where, and which crews must perform the pruning activities along the distribution network. As a result, the Non-Served Energy Level NSEL is minimized and the financial resources earmarked for this type of maintenance tasks are optimized